Excel distinguish between save & saveas (Excel XP)

How can I distinguish between the user choosing "save" as distinct from "saveAS"?

I've cobbled together the attached XLS, which i save as an XLA. It fires up well when I choose Save or saveAs, and the line<pre>MsgBox "Application Event: WorkbookBeforeSave: " & Wb.Name</pre>

makes itself known.

I have simple logic, and know how to test for not-previously-saved, which I am to treat as a save-with-new-name.
If the user tries to save a previously-saved file, I'm supposed to know that, and effect a silent .Save.
But if the user issues a saveAs, I'm to do srange and wonderful things with the filename, before effecting a .SaveAs.